Fuse



Nov. 7, 1944. ,"r. B. DOE EI'AL FUSE Filed Aug. 8, 1940 ThomasB.D

INVENTORS oe"%RobertZ.Kenv 9oZZ Z (1 1, x). /s W- ATTORNEY Patented Nov. 7, 1944 FUSE Thomas B. Doe and Robert L. Kenngott, New

York, N. Y.; assignorsgto Ford Instrument Company, Inc., Long Island City, N. Y., a corporation of New York Application August 8, 1940, Serial No. 1,894

6 Claims.

This invention relates to fuses for projectiles and more particularly to fuses for detonatin g a projectile at a desired point in its flight.

An object of the invention is to provide such a fuse for a prcjectilewhich functions upon the projectile being retarded to a velocity corresponding to the desired point in its flight to detonate the projectile.

Another object of the invention is to provide a.

fuse for a projectile in which a predetermined difference between the air pressure on the nose of the fuse and a selected air pressure set in a sealed chamber within the fuse causes the fuse to function.

Another object of the invention. is to provide a fuse for a projectile in which the firing pin or hammer which is held in an inoperative condition until the projectile has reached a predetermined point in its flight is released when the set air pressure predominates by a predetermined value.

Another object is to obtain a positive and instantaneous action when the predetermined relationship between the pressures reached.

Other objects of the invention will be apparent from a consideration of the specification and drawing in which:

Fig. 1 is a vertical cross-sectional View of an embodiment of the invention taken on line I-l of Fig. 2;

Fig. 2 is a horizontal cross-sectional view taken on line 2-2 of Fig. 1;

Fig. 3 is a partial horizontal cross-sectional view taken on line 3-3 of Fig. 1;

Fig. 4 is a partial horizontal cross-sectional view taken on line 4-4 of Fig. 1;

Fig. 5 is a view in elevation of the piston valve shown in cross-section in Fig. 1; and

Fig. 6 is a view in elevation of a stop for the valve shown in Fig. 5.

In many of the fuses in use heretofore a powder train leading from a. firing cap to the detoinvention provides a fuse which may be manufactured, shipped and stored without any powder or detonating caps therein; 'The loading of the fuse with powder and the insertion of the firing caps are such simple operations that they may be done just before securing the fuse on the projectile.

The fuse of the present invention is fired by a firing pin or firing hammer which is moved by centrifugal force acting upon the hammer mass, the hammer being held in a fixed position by a detent until the desired time of detonation. This detent is pulled out of engagement with the hammer when the projectile has reached a predetermined point in its flight.

It is well known that the air pressure on the nose of a projectile varies with the velocity of the projectile and the conditions of the atmosphere through which it passes and that the velocity of the projectile varies with the time of flight and the angle of elevation until the projectile has reached its maximum heightin the trajectory. Data for the various sizes of pronating charge in the projectile is ignited at the I time the projectile is fired and burns to the -detonating charge of the projectile in an interval of time depending on the point of ignition of the powder train. These fuses not only require that there be placed in the fuse itself a considerable amount of powder, which must be manufactured with care that the rate of propagation of the name be known and constant, but their construction has been such that they also require that the powder train be assembled with the fuse at the factory, with the attending dangers during assembly, shipment and storage.

To overcome these disadvantages, the present jectiles and initial velocities are well known and are available in easily interpretable curves and tables.

To release the detent there isprovided an opening in the nose of the fuse which is in communication with one side of a diaphragm, the other side of which is in communication with an air chamber in the fuse in which has been sealed air at a predetermined pressure. The detent is connected to the diaphragm and releases the firing hammer when the nose air pressure has been reduced to an amount such that the diaphragm is moved under the pressure of the air in the sealed chamber; The required pressure in the sealed chamber is determined by the range at which it is desired that the projectile be detonated and the difference in pressure on the two sides of the diaphragm that is necessary to snap it over from one position to another. With the type of diaphragm used in one construction, a difference of pressure of ten pounds per square inch was found necessary to snap over the diaphragm from One position to another. Thus, if it is desired to detonate the projectile at a range corresponding to a nose pressure of seventy-five pounds per square inch, the sealed air chamber would be charged to a pressure of eighty-five pounds per square inch.

It will therefore be seen that when the projectile has reached the desired range, the diawill' be snapped over and. the firing hambe released from its restrained position.

phragm mer will The hammer will then move outward against the firing cap under the action of centrifugal force created by the rotation of the shell about its central axis.

It is realized that other fuses have been disclosed whose functioning depends upon the balancing of the nose air pressure due to the velocity of the projectile against'the reaction of 'springsor the centrifugal force due to the masses of certain parts of the fuse. These mechanical parts are subject to derangement or sticking which causes unreliability in their movement. It will be apparent at once that the present invention has overcome the disadvantages inherent in these previously disclosed arrangements.

Referring to the drawing and'particularlyto Fig. 1, I represents the conical walls of 'the'fuse, which are secured to the core 2 in any conventional manner. In the core 2 is a cylindrical shaped cavity 3 in which slides, under the influence of centrifugalforce, the firing pin or firing hammer 4. The hammer 4 is shown as doubleended to provide for its functioning regardless of which direction it may be moved when released is in communication with the detonating charge inthe projectile (not shown). Firing caps 6, screw plugs 9, and ignition powder I may be placed in position just before the fuse is mounted on the projectile. p

The upper part of core 2 has an internally threaded boss I3 of such outside diameter that a passage I4 is left between chamber I5, formed by the conical walls of thefuse, and passages l6, each of which has two branches. lead to the under side of diaphragm l9 and branches I8 lead to cavity 3. By placing. the cavity 3 under the same pressure as chamber [5, it is not necessary to make detent air-tight with reference to thecore 2.

, Diaphragm I9 is held in position by its edges bearing on shoulder 20 at the'bottom of recess formed by the boss i3 of core 2 and by a shoulder 2| on member 22, which is screwed into the thread of'boss l3. To support the diaphragm l9 against excessive pressure the surface 23 of the core 2 is made co-ncave'and to insure that the air entering through passages I! will exert a pressure over the full surface of the diaphragm, concentric grooves 24 and radial grooves 25 are cut into the surface 23. Likewise, a support for diaphragm |9 in its snapped'over or upper position is had by providing. the lower concave surface of" member 22 with corresponding concentric grooves 26 and radial grooves 21. 1 .The diaphragm I9 is connected to detent 5 by a riveted or soldered head 28 on a shouldered lug 29. It is preferable that there be a slight surface of member 22 and the inner surfaces of walls I form air chamber l5.

A bore 30 in member 22 leads to the nose of the fuse and in the inner end of this bore is placed valve 3| and stop member 32. Valve 3| 4 (see Fig. 5) is cylindrical in shape and is prowall of the member 22 to permit air under pres- I bore 30 by a snap ring 3'! which cooperates with Branches clearance between the lug 29 and detent 5 so that diaphragm |9 will have begun its snapping .over action before it is required to overcome the static resistance of detent 5 with core 2. It has been found that with this clearance, the differential pressure required to snap over the diaphragm sure from an outside source (not shown) to pass through bore 30, bore 33, bore 34, and port 35 into chamber l5. Bore 34 is brought into and out of alignment with port 35 by rotating valve 3| about itslongitudinal axis by a suitable tool that fits into groove 36. Valve 3| is held in position in groove 38 in the walls of member 22 and groove 39 in the surface of valve 3|. The portion of the bore 30 between the stop member 32 "and the groove 38 serves as a valve chamber.

The limits of rotational movement of valve 3| are governed by stop 32 (see Fig. 6) which is of general cylindrical shape and whose outside diameter is the same as the diameter of bore 30. 9n the upper portion of stop 32 is a lug 40 which cooperates with a lug 4| on the lower end of valve 3| to limit the'rotation and thereby indicate the position of valve 3|.' -In the positions shown in Figs. 1 and 4, bore 34 is in communica tion with port 35 and lugs 40 and 4 I are in contact as at 42. Valve 3| can be rotated clockwise until lug 4| comes against the lug 40, as at 43, when bore 34 is out of alignment with port 35. Bore 44 in the lower end of member 22 isin communication with bore 30 by bore 45 in stop 32 and bore 33 in valve 3| I j To prevent any motion of the hammer 4 before the projectile leaves the gun upon its being fired, two oliset bores 46 are formed in core 2, as shown in Fig. 2, in which are placed springs 41. At the inner endsof' the springs 41' are mass elements 48 to which are attached pins 49 which pass through holes in hammer 4. The springs 41 are kept at tension by screw plugs 50 which are in engagement .with threaded portions 5| in core 2.

Operation 4 After the manufacture and assembly of the various mechanical-parts as shown in' Fig. 1, and assuming that it is desired to detonate the-projectile when it has reached a range corresponding to seventy-five pounds per square inch of nose pressure, a source of air is connected to bore 3|] and the chamber I5 is charged to a pressure of eighty-five pounds through bore 30,'bore 33, bore 34, and port 35. During this charging, airalso flows to the under side of diaphragm |9 through passages |4, l6 and I1, and grooves 24 and 25. Air also flows intocavity 31 through passage 18. At the same time air flows to the upper side of diaphragm I3 through bores 45 and 44. Valve 3| is then rotated 90 about itslongitudinal axis,

which seals chamber l5. Connections to the out- .side source of air are then removed andthe pressure in bores 30, 33, 34, 45'and 44 and the upper dre'd and fifteen pounds per square inch for an initial projectile velocity of 2400 feet per second, which pressure is exerted on the upper face of diaphragm I 9 causing it to snap back into the position shown in Fig. 1, with detent again in engagement with hammer 4;

As the projectile leaves the gun, it is rotated about its longitudinal axis and the centrifugal force generated by this rotation, forces mass elements 48 outward, thus leaving detent 5 as the only mechanism restraining the movement of hammer 4.

When the projectile has reached the range such that the velocity of the projectile has decreased to a value corresponding to seventy-five pounds of nose pressure, the pressure on the under side of diaphragm i9 snaps it over against the under surface of member 22. Detent 5 is thereby disengaged from hammer 4 and hammer 4 moves outward under the influence of centrifugal force and strikes one of the firing caps 6, thus igniting the powder train In, which detonates the charge in the projectile.

It is obvious that various changes may be made by those skilled in the art in the details of the embodiment of the invention disclosed in the drawing and described above within the principle and scope of the invention as expressed in the appended claims.

We claim:

1. In a fuse for projectiles, the combination of a core and a firing cap therein, a firing hammer movable in the core and adapted to strike the firing cap, a diaphragm in the core, a detent connected to the diaphragm for holding the hammer in a fixed position, an air chamber formed in part by one side of the diaphragm, a bore in the core extending axially from an opening in the nose of the fuse, said bore being in communication with the other side of the diaphragm for applying thereto the nose air pressure representative of the velocity of the projectile, a port interconnecting the air chamber and the bore, and valve means in the bore for controlling said port, said valve means being effective in one position to seal said air chamber.

2. In a fuse for projectiles, the combination of a core and a firing cap therein, a firing hammer movable in the core and adapted to strike the firing cap, a diaphragm in the core, a detent connected to the diaphragm for holding the hammer in a fixed position, an air chamber formed in part by one side of the diaphragm, a bore in the core extendin axially from an opening in the nose of the fuse, said bore being in communication with the other side of the diaphragm for applying thereto the nose air pressure representative of the velocity of the projectile, a port interconnecting the air chamber and the bore, valve means in the bore for controlling said port, said valve means being efiective in one position to seal said air chamber, and locking means engaging said hammer for preventing its movement before the projectile is fired, the said locking means being subject to centrifugal force to unlock the hammer after the projectile is fired.

3. In a fuse for projectiles, the combination of a core and a firing cap therein, a firing hammer movable in the core and adapted to strike the firing cap, a diaphragm in the core, a detent connected to the diaphragm for holding the hammer in a fixed position, an air chamber formed in part by one side of the diaphragm, a bore in the core extending axially from an opening in the nose of the fuse to the other side of the diaphragm for applying thereto the nose air pressure representative of the velocity of the projectile, a port interconnecting the air chamber and the bore, valve means in the bore for controlling said port, said valve means being effective in one position to seal said air chamber, means in the bore for stopping the movement and indicating the position of the valve means, and locking means engaging said hammer for preventing its movement before the projectile is fired, the said locking means being subject to centrifugal force to unlock the hammer after the projectile is fired.

4. In a fuse for projectiles, the combination of a core and a firing cap therein, a firing hammer movable in the core and adapted to strike the firing cap, a movable member in the core, a detent connected to the movable member for holding the hammer in a fixed position, an air chamber formed in part by one side of the movable member, a second air chamber formed in part by the other side of the movable member, a bore in the core extending axially from an opening in the nose of the fuse to the second air chamber for maintaining therein an air pressure representative of the velocity of the projectile, a port interconnecting the first mentioned air chamber and the bore, and valve means in the bore for controlling said port, said valve means being effective in one position to seal said first men tioned air chamber.

5. In a fuse for projectiles, the combination of a core and a firing cap therein, a firing hammer movable in the core and adapted to strike the firing cap, a movable member in the core, a detent connected to the movable member for holding the hammer in a fixed position, an air chamber formed in part by one side of the movable member, a bore in the core extending from an opening in the nose of the fuse to a valve chamber, a second air chamber formed in part by the other side of the movable member, a port connecting the first mentioned air chamber to the valve chamber, a passage connecting the second mentioned air chamber to the valve chamber, and valve means in the valve chamber for selectively connecting the port to the bore, said valve means including a passage permanently connecting said first mentioned passage to the bore.

6. In a fuse for projectiles, the combination of a core and a firing cap therein, a firing hammer movable in the core and adapted to strike the firing cap, a movable member in the core, a detent connected to the movable member for holding the hammerin a fixed position, an air chamber formed in part by one side of the movable member, a bore in the core extending from an opening in the nose of the fuse to a valve chamber, said valve chamber having a cylindrical wall and an end wall, a second air chamber formed in part by the other side of the movable member, a port connecting the first mentioned air chamber to the cylindrical wall of the valve chamber, a passage connecting the second air chamber to the end wall of the valve chamber and rotatable valve means in said valve chamber, said valve means having an axial passage connecting the first mentioned passage to the bore and a radial passage adapted to selectively connect the port to the bore upon rotation of the valve.

THOMAS B. DOE. ROBERT L. KENNGOTT. 

